Uses intentionally limited color palette, with certain primary colors (including additive primaries) seemingly missing altogether (and/or any variation of them). Not for flat shading (limited hue) or platform/hardware specific limitations on color.
The first video game about Limited palette was released on December 1999.
Does not refer to using less than 24bit color depth and only few things from the full range, this is about complete lack of the 3 primary colors in any form, though lacking of more minor colors can be counted if the other minor colors are obviously there. This omits simple graphics.
Mimicking limited color choices of other platforms (retro graphics) should be tagged with something else as well.